Flow-batch miniaturization

Abstract

This study introduces the first micro-flow-batch analyzer (μFBA). A simple, low-cost, deep urethane-acrylate photo-resist ultraviolet-lithographic technique was used in its development. Details of the microfabrication process are presented including; the use of two superimposed photo-masks to improve the micro-channel and stop chamber border definition, as well as integration of an LED/phototransistor photometric pair, while using an open nylon-thread (fishing line) micro-mixing system for solutions homogenization. The system was used for photometric determination of Fe(II) in oral solution iron supplements employing the well-known 1,10-phenanthroline method, with instantaneously prepared micro-chamber calibration solutions. All analytical processes were accomplished by simply changing the timing parameters in the control software. It must be emphasized here that there was no outside preparation of the standard calibration solutions; the mixing was all done in-chamber/in-line, with all solutions maintained flowing while being proportioned for the measurement processes. The μFBA results were acceptable when compared to the reference method, and comparable to normal flow-batch systems. It was possible both to project and build a low-cost probe with high sample throughput (about 120 h(-1)), low relative standard deviations (about 1.1%), and reduced reagent consumption (30 times less than the reference method). The μFBA system based on urethane-acrylate presented satisfactory physical and chemical properties while keeping the flexibility, versatility, robustness, and multi-task characteristics of normal flow-batch analyzers. The μFBA system contributes to the advance of micro-analytical instrumentation, while realizing the basic principles of "Green Chemistry".